Does not handle fgets returning an error gracefully

[mglaman]

If fgets returns false due to an error, this package will crash as it passes a bool to strpos:

TypeError: strpos() expects parameter 1 to be string, bool given in strpos() (line 109 of /var/www/html/jwtest-com/vendor/typo3/phar-stream-wrapper/src/Phar/Reader.php).

I'm still not certain how we got an error from fgets. We were trying to launch the phpstan.phar:

TYPO3\PharStreamWrapper\Phar\Reader->extractData('/var/www/html/jwtest-com/vendor/phpstan/phpstan/phpstan.phar') (Line: 53)

Relevant issue on Drupal.org. This gets triggered with:

    if (!class_exists('PHPStan\ExtensionInstaller\GeneratedConfig')) {

That causes the PHPStan\PharAutoloader to execute:

PHPStan\PharAutoloader::loadClass('PHPStan\ExtensionInstaller\GeneratedConfig')
spl_autoload_call('PHPStan\ExtensionInstaller\GeneratedConfig')
class_exists('PHPStan\ExtensionInstaller\GeneratedConfig') (Line: 589)

And we end up broken. I don't know how many lines it takes to get an error, but it's before feof returns true.

[ohader]

Thanks for reporting this. Is there a ticket in Drupal's issue tracker? I'm just trying to get some more scenario and context details. Anyway, I'll try to reproduce that behavior soonish.

That's the position that triggers the TypeError:
https://github.com/TYPO3/phar-stream-wrapper/blob/master/src/Phar/Reader.php#L109

If possible, please provide the version of phpstan.phar that has been used and a debug_print_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS ) in case $line === false.

[ohader]

Okay... independent from PharStreamWrapper I could reproduce fgets resolving to false at the end of a file offset, without(!) having feof() === true. Basically I was reading 2-byte chunks from a total of 13 bytes. I was able to reproduce that on macOS with PHP 7.4, but not with PHP 8.0. Well...

I think it's fine to add an additional guard for this case. Still, finding out what really happens with phpstan.phar of course would be interesting.

[ohader]

@mglaman Please let me know whether PR #70 fixes the issue for Drupal. Thx

[mglaman]

Sorry! I linked this GitHub issue to the Drupal issue, but not here to there. Drupal issue: https://www.drupal.org/project/upgrade_status/issues/3232011

[mglaman]

I was able to reproduce that on macOS with PHP 7.4, but not with PHP 8.0. Well...

I had PHP 8.0, locally maybe that's why I couldn't reproduce. I'll see if I can work the user to get a reproduction and more data.

[ohader]

Let's have a look, when that actually happens - thus, when PHP has problems to read from a stream, without issuing feof.

https://github.com/php/php-src/blob/PHP-7.4.20/ext/standard/file.c#L1122-L1127

false is returned when underlying stream invocation returns null, let's have a look...

https://github.com/php/php-src/blob/PHP-7.4.20/main/streams/streams.c#L991-L996

null is returned nothing could be read from a stream (zero bytes copied to memory).

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tl;dr: fgets($resource) returns false, when not a single byte could be read from a string, as indicated by variable total_copied.

I have not able to reproduce this behavior with DDEV and PHP 7.4.20 on macOS.